Longer Limbs

Animals that live in cold climates tend to have stubby limbs—shorter arms and legs—even smaller ears and tails. Picture a penguin and you’ll see what I mean. Biologists have long assumed that these stumpy appendages are an evolutionary adaptation. Shorter extremities minimize heat loss, so animals that are more compact are better suited to the cold.

But scientists from Ohio say that temperature may have a more direct effect on the length of an animal’s limbs. Because they find that turning up the heat helps cartilage grow—results that were published in the Proceedings of the National Academy of Sciences.

The researchers raised mice at several different temperatures, and they confirmed that those kept at a balmy 80 degrees were longer limbed than those who lived at a more chill 45. But how does a little heat make mice more leggy? The answer, they find, lies in the cartilage. Long bones grow from the cartilage found at either end. And the warmer it is, the more that cartilage grows, even when it’s just sitting in a test tube. Which I guess means it’s possible that the dog days of summer lead to longer-legged dogs.

更長的四肢

生活在寒冷地方的動物其四肢傾向于長得短而粗——就是耳朵和尾巴也要小一些。想想企鵝你就明白我的意思了。生物學家們長久以來認為這些短而粗的附肢是一種進化過程中的適應。更加短小的四肢能使熱損失降到最低，所以，體型粗短的動物能更好地適應寒冷氣候。
 
不過來自俄亥俄 (Ohio)的科學家們報道說，溫度可能對動物四肢的長度有更直接的影響。因為，他們發(fā)現提高溫度能幫助軟骨組織的生長——這些研究結果發(fā)表在《美國國家科學院院刊》(Proceedings of the National Academy of Sciences)上。

研究者們在不同的溫度下飼養(yǎng)老鼠，他們證實與生長在寒冷的45度 （譯者注：這里指華氏度，45華氏度相當于7.2攝氏度）下的老鼠相比，那些生長在溫和的80度 （80華氏度相當于26.7 攝氏度 ）下的老鼠的四肢要長一些。但是溫度的提高是怎樣使老鼠的腿長得更細長的呢？研究者們發(fā)現答案在于軟骨組織。長的骨骼是從骨頭兩端的軟骨組織生長而來。氣溫越暖和，軟骨組織長得越長，即使在試管中也是如此。根據這個研究，我猜想這可能意味著炎熱的夏天會使狗的腿長的更長。

Vocabulary:

Limb: 四肢
Stubby: 短而粗的
Penguin: 企鵝
Assume: 假設；
Stumpy: 樹墩似的；短而粗的
Appendage: 附屬物
Evolutionary: 進化的
Extremities: (醫(yī)學)四肢，手足
Minimize: 最小化
Compact: 緊密的；簡潔的
Cartilage: 軟骨組織
Confirm: 確認
Balmy: （氣候）溫和的
Chill: 寒冷的
Leggy: 腿細長的；露腿的
The dog days of summer： 夏季最悶熱的時候